Acetylation of compounds containing a-co-(ch2)x-co-group



UNITED STATES PATENT OFFICE ACETYLATION OF COMPOUNDS CONTAIN- ING A -C-(CH2)x-C0 GROUP David 0. Hull and Albert H. Agett, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 19, 1946, Serial No. 704,524

7 Claims. (Cl. 260-483) This invention relates to a method of acetylatperature elevated to a point at which refluxing ing keto-compounds containing a occurs in order to promote the reaction. Nevertheless, the process can be carried out in an autoclave and temperatures up to 100 C. .or even as group and malonic acid esters using isopropenyl 5 much as 3000 can be employed prepare the acetate and a catalyst, usually an acid catalyst.

Often it is desirable to introduce acetyl groups into organic compounds to impart desired propt 323 23 233 mi gg fi g gg? l0 and then neutralize the catalyst and distill under Compounds containin a CQ. (CH2) reduced pressure to obtain the desired product or group and malonic acid esters. Some of the compounds of this type are S-diketones and acetate and the compound containing v-diketones, [i-ketoesters, -ketoesters and malol5 nic acid esters. In the formula results in a mixture of acetylated products. In that case it is desirable to selectively distill the as used herein :1: represents an integer of 1 or 2.

Any of the compounds of thls type can be readlly 'fihz icfl l ov vi g gig r nfal s ifiustrate our invenacylated by reacting" thereon with isopropenyl tion' acetate and a catalyst.

One object of our invention is to prepare acetyl- Example 77 of lsopropenyl acetate ated products of compounds Containing were m xed Wl h 1 0 grams of acetoacetic ester containing 6 drops of sulfuric acid. The mass CQ (CHZ)1 CO' was then heated in a distillation apparatus at atmospheric pressure (740 mm). When the temizs. Other objects of our invention will perature had reached 58 0., 24.5 grams of acetone appear herein. had been distilled off. Magnesium carbonate was Our invention is carried Ou y reacting added to the mass to neutralize the catalyst and p o vl acetate wlth a fi-dlketone and a v so it was then distilled under reduced pressure n a B-ketoester, a v-ketoester or a melonic (3 mm). 37 grams of the C-acetylated derivaacid ester in th pr O a Catalyst Orditive of the acetoacetic ester were obtained. The

narily it is desirable to dissolve the catalyst in resulting product b i t; 72-75 c, t 3 m, the p op y eeetete and then add the pressure and had an equivalent weight of 89. comp n n min h C H2 group and Example 2. grams of ethyl acetoacetate O T the eey co p under diminished enol acetates which had been formed were dispressure. tilled off at 94 C. and 10 mm. pressure. The

Although ordinarily sulfuric acid is selected as yield was 92%. the catalyst in an acetylation process in accord- Example 3.A mixture was prepared of 100 ance with our invention, it is to be understood 4.5 grams .of acetyl acetone, 200 grams isopropenyl catalyst employed may be an acid or it may be a was refluxed, and the acetone was distilled oiT. tertiary nitrogenous material. Some acids which The acetylation catalyst was neutralized with are useful for c a y processes n accordance sodium acetate, and the mass was distilled at with our invention are sulfuric acid, p-toluene 5 10 mm. pressure. grams of the monoenol sulfonic ac d, Se e acid. y Sulfamie ac acetate were obtained having a boiling point of, zinc chloride and boron trifiuoride etherate. 84 C. at 10 mm. pressure, and 27 grams of di- Other compounds useful as catalysts are triethyl acetate were obtained having a boiling point of amine, pyridine and benzyl dimethyl amine. 114 C. at 10 mm. pressure.

Ordinarily it is only necessary to employ a tem- 55 Example 4.- grams of isopropenyl acetate were mixed with 160 grams of diethyl malonate and 6 drops of sulfuric acid were added. The mass was heated in a distillation apparatus at atmospheric pressure. The acetylation proceeded rapidly and 9.7 grams of acetone were recovered at 50-58 C. Magnesium carbonate was then added to the mass to neutralize the sulfuric acid. The unreacted isopropenyl acetate was removed at 90-100 C. The mass was then distilled at a temperature of 115-120 C. and 1'1 mm. pressure. 20 grams of acetyl ethyl malonate were recovered.

Example 5.-100 parts of acetyl acetone were mixed with 200 parts of isopropenyl acetate containing 1 part of zinc chloride. The solution was heated at total reflux for 2 hours. Distillation gave 56 parts of acetone. The residue was then distilled under reduced pressure. There was obtained 34 parts of the monoenol acetate of acetyl acetone and '72 parts of triacetyl methane, boiling point 103-4 C. at 20 mm. pressure.

Example 6.--100 parts of ethyl acetoacetate were mixed with 1 part of selenic acid in 200 parts of isopropenyl acetate. The solution was refluxed for 6 hours. Distillation gave 54 parts of acetone. The excess isopropenyl acetate was removed by distillation at atmospheric pressure and a temperature of 90-100 C. The residue was distilled at reduced pressure, and 102 parts of diacetyl ethyl acetate, boiling point 8890 C. at 10 mm. pressure was obtained.

Example 7 .100 grams of isopropenyl acetate were mixed with 5'7 grams of acetonyl acetone and 6 drops of'sulfuric acid. The mixture was fractionated at atmospheric pressure (740 mm.). At 55-60 C., 54.4 grams of acetone were off. At 92-96 C. 43.7 grams of 2,5-dimethyl furane were distilled over, giving a good conversion of acetonyl acetone to 2,5-dimethyl furane.

Example 8.-'72 grams of ethyl levulinate (a 'y-ketoester) were mixed with 100 grams of isopropenyl acetate and drops of sulfuric acid. The mass was heated at reflux, and the acetone formed was distilled off. At the end of one hour the catalyst was neutralized, and the enol acetates formed were distilled from the mass at 89 C. and 5 mm. pressure. A yield of 45 grams was obtained.

In the above examples, other compounds having -CO-CH2-CO groups may be acetylated using isopropenyl acetate and an acid catalyst. For instance, in the B-diketones, -y-diketones, and ketoesters and ,B-ketoesters other alkyl groups than methyl be present in the compounds employed, and the reactions will go in the same manner as described in the examples.

Ordinarily the acetylation of compounds containing -CO-(CH2)m-CO- results in a, mixture of C-acetylated and O-acetylated products. In many processes the O-acetylated product (the enol acetates) predominates and the C-acetylated product is minor in proportion. In other cases, such as by the processes of Examples 4, 5, and 6 or where certain catalysts, such as selenic acid are used, the formation of predominates. The O-acetylated and C-acetylated products may be separated by distilling at reduced pressure as illustrated by Example 3. Our invention includes the acetylation generally of compounds containing -CO-CH2-CO- with isopropenyl acetate regardless of whether the C- acetylated or the O-acetylated products predominate.

What we claim and desire to secure by Letters Patent of the United States is.

distilled C-acetylated products R being alkyl and R 1. A method of acetylating a compound having the formula:

0 ll C-R in which R is alkyl and R is a group selected from alkyl and ethoxy, ac being an integer of not more than 2 which comprises reacting thereon with isopropenyl acetate in the presence of an esterification catalyst selected from the group consisting of sulfuric acid, p-toluene sulfonic acid, selenic acid, N-acetyl sulfamic 'acid, zinc chloride, boron trifluoride etherate, triethylamine, pyridine and benzyl dimethylamine.

2. A method of acetylating a compound having the formula:

R and R' being alkyl and a: being an integer of not more than 2 which comprises reacting thereon with isopropenyl acetate in the presence of an esterification catalyst selected from the group consisting of sulfuric acid, p-toluene sulfonic acid, selenic acid, N-acetyl sulfamic acid, zinc chloride, boron trifiuoride etherate, triethylamine, pyridine and benzyl dimethylamine.

3. A method of acetylating a compound having the formula:

0 ii R acetylating a compound hav- 9 t R (CH2):

II o R and R being alkyl groups and I being an integer of not more than 2 which comprises reacting thereon with isopropenyl acetate in the presence of a sulfuric acid catalyst.

5. A method of acetylating a compound having the formula:

0 )LR H1),

ll 0 being ethoxy and a: being 6 an integer of not more than 2 which comprises REFERENCES CITED reacting thereon with isopropenyl acetate in the presence of a sulfuric acid catalyst. i l; ig g i fi are of record in the 6. A method of acetylating acetyl acetone p which comprises reacting thereon with isopro- 5 UNITED STATES PATENTS peny] acetate in the presence of sulfuric acid. b

7. A method of acetylating ethyl acetoacetate 2 52 g g g which comprises reacting thereon with isopro- Hansley penyl acetate in the presence of sulfuric acid.

2,407,301 Spence et a1. Sept. 10, 1946 DAVID HULL- 2,407,302 Spence eta] Sept.10,1946 ALBERT H. AGE'I'T. 

